Graphene Mechanics: Current Status and Perspectives

Galiotis, Costas; Frank, Otakar; Koukaras, Emmanuel Ν.; Sfyris, D.

doi:10.1146/annurev-chembioeng-061114-123216

Cited by 83 publications

(85 citation statements)

References 98 publications

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“…Two dimensional (2D) layered solids such as graphite comprise of single layers held together via van der Waals forces and possess extraordinary mechanical properties 1 . This weak interlayer coupling affects significantly the properties of multi-layers.…”

Section: Introductionmentioning

confidence: 99%

Tunable macroscale structural superlubricity in two-layer graphene via strain engineering

et al. 2020

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Achieving structural superlubricity in graphitic samples of macro-scale size is particularly challenging due to difficulties in sliding large contact areas of commensurate stacking domains.Here, we show the presence of macro-scale structural superlubricity between two randomly stacked graphene layers produced by both mechanical exfoliation and CVD. By measuring the shifts of Raman peaks under strain we estimate the values of frictional interlayer shear stress (ILSS) in the superlubricity regime (mm scale) under ambient conditions. The random incommensurate stacking, the presence of wrinkles and the mismatch in the lattice constant between two graphene layers induced by the tensile strain differential are considered responsible for the facile shearing at the macroscale. Furthermore, molecular dynamic simulations show that the stick-slip behaviour does not hold for achiral shearing directions for which the ILSS decreases substantially, supporting the experimental observations. Our results pave the way for overcoming several limitations in achieving macroscale superlubricity in graphene.

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Section: Introductionmentioning

confidence: 99%

Tunable macroscale structural superlubricity in two-layer graphene via strain engineering

et al. 2020

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“…Therefore, the development of an efficient method for obtaining the homogenous dispersion of CNTs within cement matrix turned out to be an extremely challenging task. In particular, the graphene's unprecedented mechanical properties [22,23] make it one of the most promising nanomaterials for application in composites, [24] and in particular for civil engineering applications. [13] The addition of CNTs can, in particular, enhance the mechanical properties of cement composites [11,[15][16][17] (see Table 1), refine their pore structure, [11,[14][15][16] and reduce the drying shrinkage.…”

Section: Introductionmentioning

confidence: 99%

High‐Performance Graphene‐Based Cementitious Composites

et al. 2019

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This study reports on the development of a cementitious composite incorporating electrochemically exfoliated graphene (EEG). This hybrid functional material features significantly enhanced microstructure and mechanical properties, as well as unaffected workability; thus, it outperforms previously reported cementitious composites containing graphene derivatives. The manufacturing of the composite relies on a simple and efficient method that enables the uniform dispersion of EEG within cement matrix in the absence of surfactants. Different from graphene oxide, EEG is found to not agglomerate in cement alkaline environment, thereby not affecting the fluidity of cementitious composites. The addition of 0.05 wt% graphene content to ordinary Portland cement results in an increase up to 79%, 8%, and 9% for the tensile strength, compressive strength, and Young's modulus, respectively. Remarkably, it is found that the addition of EEG promotes the hydration reaction of both alite and belite, thus leading to the formation of a large fraction of 3CaO·2SiO 2 ·3H 2 O (C‐S‐H) phase. These findings represent a major step forward toward the practical application of nanomaterials in civil engineering.

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“…and βG are the G mode's Grüneisen parameter and shear deformation, respectively, and ν is the Poisson ratio. For fully supported samples, the shift rates are governed by the Poisson ratio of the polymer, taken as 0.33, which gives ~ -31 and -10 cm -1 /% for / stress transfer 1,20. From that, γG = 1.99 and βG = 0.99.…”

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Strain Assessment in Graphene Through the Raman 2D′ Mode

et al. 2015

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Accurate and simple local strain assessment in graphene is one of the crucial tasks in device characterization. Raman spectroscopy is often used for that purpose through monitoring of the G and 2D modes. However, the shifts of those two bands might be biased, especially under uniaxial strain, by the effects of charge-transfer doping. Therefore, it is extremely desirable to use another Raman band, less affected by doping, but with a defined and measurable behavior under strain.The Raman 2D' mode is in this sense the ideal feature for the evaluation of strain levels in stretched graphene monolayers, suitable for this task even under different experimental conditions. The sensitivity and accuracy of the approach through 2D' mode is on the same level as through the G mode, however, the clear advantage of the 2D' arises when doping effects are present in the sample.On top of that, since the value the 2D' splitting is used for the strain level quantification, and not the shift rates of the components, the doping effects should not influence this value even if present. The close proximity of our value, incl. a small 95% confidence interval, to the one predicted in 38 points to the viability of both the presented experimental and previous theoretical 38 results. AUTHOR INFORMATION

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Graphene Mechanics: Current Status and Perspectives

Cited by 83 publications

References 98 publications

Tunable macroscale structural superlubricity in two-layer graphene via strain engineering

Tunable macroscale structural superlubricity in two-layer graphene via strain engineering

High‐Performance Graphene‐Based Cementitious Composites

Strain Assessment in Graphene Through the Raman 2D′ Mode

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